Following revelations on Monday that Jared Kushner and Ivanka Trump used at least three private email accounts to conduct official White House business, a report on Tuesday contained a new, explosive detail about the private email use by the two top White House advisors who are also the son-in-law and daughter of Donald Trump himself.

As the investigation into their use of private email servers and accounts intensified last week, Kushner and Ivanka Trump switched their email accounts from servers owned by the Microsoft Corporation to private servers operated by the Trump business organization, according to the exclusive report by the national newspaper USA Today.

On December 31 of last year, Kushner and Trump created their own private email domain, ijkfamily.com, presumably for their family correspondence. But on either September 26 or 27 — about one week ago — the couple moved their ijkfamily.com domain to servers that cybersecurity experts identify as belonging to the Trump Organization, according to the USA Today investigation. Read the entire USA Today report on the Kushner and Trump email server switch by accessing this link.

The initial revelation that Kushner was using a private email account to conduct official United States government business appeared on the political news site Politico on September 24. Kushner’s own lawyer, Abbe Lowell, confirmed to the site, as well as to the New York Times, that Kushner had indeed used the private account for official emails.

The move to Trump-owned servers also came approximately one week after Russia investigation Special Counsel Robert Mueller requested that the White House hand over a large cache of internal documents that could shed light on how Donald Trump and members of his administration have dealt with Russia.

Kushner, it was revealed over the summer, held four meetings with Russian officials that he had initially concealed. In addition, in May it was revealed that Kushner had attempted to set up a secret and secure “back channel” method to communicate directly with the Russian government that would not be subject to scrutiny by United States intelligence services.

A direct link to the ijkfamily.com domain connects to a page operated by the popular web hosting service GoDaddy. But according to online records, Kushner and Ivanka Trump use Microsoft Office 365 as their email server software. In 2014, Microsoft announced a “strategic partnership” with GoDaddy to allow more users to utilize the Office 365 software.

While the exact content of the government emails sent and received by Kushner and Ivanka Trump — such as whether any of the emails contain sensitive or classified information — is not yet publicly known, storing the official correspondence on a server owned by the Trump businesses “certainly creates the appearance of potential impropriety,” and raises worrying questions about who might be able to access the emails on the private Trump servers, according to former federal prosecutor Renato Mariotti.

Donald Trump has assigned Kushner a number of high-profile and potentially sensitive government tasks — including leading negotiations for a peace deal between Israel and the Palestinians.

In January, shortly after Donald Trump’s inauguration, the U.S. National Security Agency warned Trump and his top White House officials against using private email accounts for any type of official correspondence, according to a Politicoreport. Because Trump has given Kushner a top government position with high responsibility, he is a prime target for foreign espionage agencies, cybersecurity experts say.

“Jared is probably one of the top five or 10 targets in the U.S. government,” former government cybsersecurity advisor Richard Clarke said. “It’s a pretty safe bet that his personal devices have been compromised by foreign intelligence services. And therefore there is some risk that meetings he attends are compromised too.”

According to the NSA briefings given to Trump and his top aides in January, Kushner could cause “a significant security breach” by using private email accounts and servers.